Neon (Ne)

• Element Symbol: Ne
• Atomic Number: 10
• Atomic Mass: 20.1797
• Group # in Periodic Table: 18
• Group Name: Noble gases
• Period in Periodic Table: 2
• Block of Periodic Table: p-block
• Discovered by: Sir William Ramsay, Morris W. Travers (1898)

Neon is normally a colorless, odorless, inert gas. However, when stimulated in a vacuum tube, it glows reddish-orange. Also, despite its lack of chemical reactivity, neon was important in proving the existence of isotopes. Its density is about two-thirds the density of air. This element is monatomic. Its atomic number is 10, and its chemical symbol is Ne. Neon is one of the so-called noble or inert gases that can be found in group 18 in the periodic table. This group also includes helium, krypton, argon, xenon, and radon. All of the noble gases are very unreactive chemically. These gases only react under extreme conditions. In the past it was believed that neon and the other noble gases could not react with any of the other elements. Eventually, it was discovered that a few hundred compounds are in fact made from the noble gases. The name "noble" was borrowed from the noble metals such as silver, gold, and platinum because they are also very nonreactive.

Neon was discovered in 1898 by William Ramsay and Morris Travers at University College London. The two also discovered the elements krypton and xenon. These three noble gases were found using the method of fractional distillation. This method separates liquid air into several different components. Ramsay and Travers named neon after the Greek word néos, which means "new."

Despite its lack of chemical reactivity, neon was important in proving the existence of isotopes. Specifically, in 1912 the English radiochemist Frederick Soddy suggested that the existence of isotopes was the only way to explain the products of radioactive decay. A year later, the British physicist J. J. Thomson found proof of their existence. He observed that a stream of neon atoms exposed to a magnetic field gave off two beams, and he therefore concluded that some neon atoms were heavier than others.

Physical Properties

Neon is normally a colorless gas. However, when it is placed in a vacuum tube and stimulated, it glows reddish-orange. Like the other noble gases, neon is odorless. Neon’s standard state at 298 kelvins (K) is a gas. Its density of 0.0009 grams per cubic centimeter (g/cm³) is two-thirds that of air. The melting point and boiling point of this noble gas are within 2.5 degrees Celsius (°C) of each other, at −248.5 °C and −246 °C, respectively. In other words, neon is only a liquid within an exceptionally small range of extremely low temperatures.

Chemical Properties

Chemically, neon is inert. This means that it is an element that is not very reactive. In other words inert gases will only react under extreme conditions because they all consist of only a single atom, with complete pairs of electrons in each shell. Neon’s ten electrons consist of five electron pairs, which means that this noble gas is highly unlikely to react with other elements because it is complete by itself. The term "complete" in this context means that the element is not missing any electrons or that every electron is paired off.

Since all of the noble gases show extremely low chemical reactivity, only a few hundred noble-gas compounds have ever been formed. Neutral compounds combining helium and neon with other elements do not exist at all. As for the other four noble gases, they have shown only minor reactivity with oxygen. Neon is the least reactive of the noble gases, followed by helium, argon, krypton, xenon, and radon.

Naturally occurring neon is made up of a mixture of three stable isotopes: are neon-20 (90.5 percent natural abundance), neon-21 (0.3 percent), and neon-22 (9.2 percent). These three stable isotopes of neon were important in proving to theoretical chemists the existence of isotopes. Neon also has sixteen radioisotopes with mass numbers ranging from 16 to 34. All sixteen are short-lived, with half-lives ranging from around three minutes to under one second.

Applications

Neon is the fifth most abundant element in the universe by mass (1,333 parts per million), after hydrogen, helium, oxygen, and carbon. It is formed when helium and oxygen nuclei fuse together. However, despite neon’s massive abundance in the universe, it is very rare on Earth, found in concentrations of about 18.2 parts per million in Earth’s atmosphere—and in even smaller amounts (70 parts per billion) in Earth’s crust. This relative scarcity on Earth is due to the element’s physical and chemical properties. The so-called noble properties make it very difficult for neon to form the types of solid ores that are found in Earth’s crust. These properties also make it difficult for neon to exist in higher concentrations in Earth’s atmosphere.

Neon is produced using extraction by fractional distillation of liquid air. This process separates the liquid air into several different fractions, or components. In neon’s case fractional distillation gives a fraction that contains both helium and neon. The helium is removed from the mixture with activated charcoal. Only a few tons of neon are produced annually to meet commercial needs, although it is possible in theory to produce more of this noble gas because 65 billion metric tons of it are currently circling Earth in outer space.

Due to its noble properties, neon has a variety of useful applications. Historically, neon was often used in the neon signs that glow an unmistakable bright reddish-orange. As for its modern-day uses, neon is used in a number of commercial applications, including—but not limited to—vacuum tubes, high-voltage indicators, TV tubes, and helium-neon lasers. Liquid neon is used commercially as a refrigerant or coolant to produce very low temperatures. Although liquid neon cannot achieve the temperature of liquid helium (−269 °C), it can maintain a temperature of −246°C.

Bibliography

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Emsley, John. Nature’s Building Blocks: An A–Z Guide to the Elements. 2nd ed. New York: Oxford UP, 2011. Print.

Haynes, William M., ed. CRC Handbook of Chemistry and Physics. 95th ed. Boca Raton: CRC, 2014. Print.

"It’s Elemental: The Periodic Table of Elements." Science Education at Jefferson Lab. Thomas Jefferson Natl. Accelerator Facility, n.d. Web. 25 Sept. 2015.

"Neon Element Facts." Chemicool. Chemicool.com, 17 Oct. 2012. Web. 18 Sept. 2015.

Travers, Morris William. The Discovery of the Rare Gases. London: Arnold, 1928. Print.